With higher-speed inter-LSI signals, it has become difficult to solve the problems of greater noise and power consumption by using electric transmission. In view of these problems, attempts have been made to carry out inter-LSI transmissions using light, which has substantially no electromagnetic interference and no frequency-dependent loss. For example, Japanese Laid-open Patent Application No. 2006-59867 describes an optoelectric conversion header (optoelectric conversion module) that is used for inter-LSI optical transmissions and is provided with an optoelectric conversion device and a ferrule which is insert-molded with a lead and into which an optical fiber is inserted. In this optoelectric conversion module, the optoelectric conversion device and the optical fiber have a direct optical connection without the use of a lens or another optical component. In this case, the optoelectric conversion device is a light-emitting device (e.g., Vertical Cavity Surface Emitting Laser (VCSEL)) or a light-detecting device.
FIG. 10 is a cross-sectional view of the essential part of such a conventional optoelectric conversion module showing the flow of resin when the resin is molded during manufacture of the module. An optoelectric conversion module 1 is manufactured by first mounting an optoelectric conversion device 9 on a ferrule 3 having a through-hole (fiber through-hole) 7 through which an optical fiber (or optical waveguide) 5 is inserted. In this case, the optoelectric conversion device 9 and the electrode (not shown) of the ferrule 3 are connected, for example, by the heat pressure welding of an Au bump 11. Next, the optical fiber 5 is inserted into the ferrule 3. The optical fiber 5 is thereby positioned in the optoelectric conversion device 9. Lastly, the ferrule 3 and the optoelectric conversion device 9 are molded using resin (not shown).
The module 1 into which the optical fiber 5 has been inserted is mounted on a circuit board (not shown), connected with an optoelectric conversion device driver ICs (driver, receiver, or the like) via a bonding wire. Then the ferrule 3, the optoelectric conversion device 9, the optoelectric conversion device driver ICs, and the circuit board are monolithically molded using resin. With the module 1, a smaller size and lower costs can be expected because the optical fiber 5 is directly inserted into and connected to the ferrule 3 that is to be mounted on the board.
However, unlike ordinary electrical components, the module 1 cannot be mounted on the circuit boards using high-temperature heating process, such as reflowing, because the coating resin of the mounted optical fiber 5 degrades at high temperature. Also, mounting using high-temperature heating is not possible for the same reasons when a module in which the module 1 is mounted (that is to say, in which an optoelectric conversion device, a ferrule, and a circuit board are monolithically molded using a resin) is incorporated in an apparatus-side board, and this is an obstacle to the mass production of optoelectric information processors. In contrast, if the assembly of the optical fiber 5 is omitted, the resin that is used for molding the optoelectric conversion device 9, the ferrule 3, and the circuit board enters, as shown by the arrow in FIG. 10, from the opening 7a of the fiber through-hole 7 formed at one end 3a of the ferrule 3 and later becomes an obstruction to the insertion of the optical fiber 5.